Fluid deprivation in enuresis - Effect on urine output and plasma argininevasopressin

Desmopressin responders tend to have a large volume of urine production at night, in contrast to desmopressin refractory patients who often produce no rmal volumes of urine. Controls and adolescent/adult primary monosymptomati c nocturnal enuretics were included in a study measuring urine volume and p lasma vasopressin levels before and during a 24-hour water deprivation test . The results indicate a significantly higher urine production in desmopres sin responders when compared with controls and non-responders. Before fluid deprivation, only the nocturnal polyuric patients showed a urine osmolalit y significantly lower than that of controls and desmopressin non-responders . A significant decrease in the clearance of osmols was evident in the desm opressin refractory group from day to night. All three groups showed a sign ificant increase in plasma vasopressin during fluid deprivation, with polyu ric, desmopressin-responding patients showing a lower increase that the non responders and controls. Plasma vasopressin levels were normal in adolescent and adult enuretics reg ardless of their response to desmopressin. Moreover, response to fluid depr ivation in both polyuric and enuretic patients resulted in a significant de crease in urine output from the first to the second night.